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training, and comprehensive inspections requirements. Stormwater management features are <br /> inspected on a quarterly basis and following significant precipitation events. <br /> Meteoric water that falls on the affected lands boundary is controlled through sediment control <br /> ponds or is allowed to collect near the main entrance where it either infiltrates or evaporates prior to <br /> leaving the property boundary. The SWMP is updated on a regular basis as control features on the <br /> mine site change. A copy of the current SWMP is provided in Appendix 2. <br /> 9.3 Passive Mine Water Treatment <br /> The following discussion of mine water discharge management is broken into three segments, <br /> describing the treatment process and changes in configuration for each of the three ponds. Each of <br /> the ponds was expanded to accommodate the passive treatment system, to accommodate additional <br /> flows should such capacity be required in the future, and to contain flows from a 10 year 24 hours <br /> storm event. The ponds and water conveyances associated with the passive treatment system are <br /> lined (a combination of membrane and clay liners) or contained in pipe. <br /> - Chemical Flocculant—the first stage of the treatment system is the option to use a <br /> chemical flocculant to encourage settlement of total suspended solids in the mine water <br /> as it exits the portal. A drum of ferric chloride outfitted with a small pump can be used <br /> to enhance settling in the mine water as it enters the first pond. Chemical flocculant is <br /> used on an as needed basis. <br /> - Mine Water Pond# 1 is the first pond encountered by mine water after it leaves the <br /> portal. The pond size was increased, and Collection Ditch 2 was routed into Pond#1 to <br /> allow for the pond's expansion. Outfall 001A remains in place under Modification 5 of <br /> CDPS permit CO-0000003 although this outfall is not currently used as a discharge <br /> point. This pond contains settling capacity, a silt curtain removes additional sediment, <br /> and a sand filter to further filter the water and to remove sediment before it enters the <br /> anaerobic bioreactor cell (Mine Water Pond #2). Two feet of free board will be <br /> maintained in Mine Water Pond #1, as demonstrated by area capacity curves. Pond# 1 <br /> is lined with a combination of an HDPE liner(reused from the original mine water <br /> pond) and clay liners to create a pond that contributes to the natural environment with <br /> perimeter vegetation growth, as requested by the Army Corps of Engineers during a <br /> 2017 inspection. <br /> - Mine Water Pond#2 (formally Pond#2) has been expanded and reconfigured to serve <br /> as a sulfate reducing bioreactor. Organic material (e.g., manure, straw, and wood chips) <br /> along with limestone are used to support bacterial growth. The pond is lined and <br /> maintained in a saturated state. Water from Mine Water Pond #1 is piped under the <br /> substrate and allowed to flow up through the bioreactor where sulfates in the water are <br /> M-2012-032 <br /> Amendment 02 Exhibit U <br /> December 2021 U-24 <br />